<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>伪元素选择器使用场景2-仿土豆网显示隐藏遮罩案例</title>
    <style>
      .tudou {
        position: relative;
        width: 444px;
        height: 320px;
        background-color: pink;
        margin: 30px auto;
      }

      .tudou img {
        width: 100%;
        height: 100%;
      }

      .tudou::before {
        content: "";
        /* 隐藏遮罩层 */
        display: none;
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.4) url(images/arr.png) no-repeat center;
      }

      /* 当我们鼠标经过了 土豆这个盒子，就让里面before遮罩层显示出来 */
      .tudou:hover::before {
        /* 而是显示元素 */
        display: block;
      }
    </style>
  </head>

  <body>
    <div class="tudou">
      <img src="images/tudou.jpg" alt="" />
    </div>
    <div class="tudou">
      <img src="images/tudou.jpg" alt="" />
    </div>
    <div class="tudou">
      <img src="images/tudou.jpg" alt="" />
    </div>
    <div class="tudou">
      <img src="images/tudou.jpg" alt="" />
    </div>
  </body>
</html>
